Gear



Dec. 4, 1928. 1,693,740 E. WILDHABER GEAR Filed Aug. 6. 1926 4 Sheets-Sheet i INVENTOR Ernest Wildhaber ATTORNEY f Dec. 4, 1928.

E. WILDHABER GEAR Filed Aug. 1926 4 Sheets-Sheet 2 'INVENTOR mast Wildhaber ATTORNEYZL & F19

Dec. 4, 1928.

INVENTOR Ernest Wildlzaber Dec. 4, 1928.

' E. WILDHABER GEAR Filed Aug. 6, 1926 '4 Sheets-Sheet 4 mvsmon Emast- Wzidhaber ATTORNE Patented Dec. 4, 1928.

UNITED STA res PATIE ROCHESTER, NEW YORK, A CORPORATION or NE YORK;

GEAR.

Application filed Auguste, 1926. Serial Il'o. 127,618.

The present invention relates to gears and particularly to gears provided with long"- tudin-ally curved teeth.

One object of the present invention is to provide a neivandjefiicient system of curved tooth gearing which maybe simply, quickly and cheaply produced.

Another object oi? the invention. is the p ovision of a system of curved tooth gearing" in which one member canbe cut by a hob Without the usual-generating roll, with the result ant advantages ot'gincreased simplicity and speedot production.

A- further object ot'the invention is to provide a form of longitudinally curved tooth gear which Will mesh Rvithlinecontact With a WQlYIIL'Ol with a mating bevelgea'r. v

Other objects of the. invention Willbe apparent hereinafter from the specification and from the recital of the appended claims;

This application "is a continuation in part.

,ing diagrammatically a .hobbingr cutter arranged'in cutting contact therewith;

2 is a sectional plan view of a portion of the gear on the line 2;.2 oi 1, showing diagrannnatically also the relative positions of gear and hob duringthe production of the gear;

Fig. 3 is a sectional view of a portionlot'th gear taken on the line 3+-3 of Fig. 1;

Fig. 4 is a diagrammatic plan vievrota pair of hyperboloiclarl gears in inter-meshing relation; a

' 5 is aside elevation of thesame;

6 is adiagrammatic plan view further illustrative of the principles underlying the present invention and showing the relation between the hobs employed in cutting pair of gears according to this invention g Figs 9 and 10 are similar viewsLillustrate mg diagrammatically the method of produc mg a bevel pinion w th this invention;

F ig. 11 is a side elevation oi ataper hob such as might be employed :in pi'oducin'g" gears according to this invention ;1 i

Fig. 12 is a fragmentary end view of the same; j Fig. 13 is a side elevation ota pair otbevel gears produced according to this invention; and r F ig. 14 is a side elevation showing a taper Worm in mesh with gear such as shownlin" Fig-,1. V j .j I The presentinvention is a re Lllt oteltorts to simplify and expedite and cheapen the commercial production of ,eiiici-ent. curved tooth gears.- This invention has as its basis the discovery of a form of tapered gear which can be produced in. a hobbing' or CQl'ltlIlUOHS indexing operation Without the usual genei? ating roll and which can be meshed selectively Wltl'l af worm, corresponding to the hob employed to produce the gear 'or With'a mating gear produced in a generating operation.

The gear Which tormsfthe basis oiuns 1n-' ur orriclil};

ERNEST WILDHABERyOF ROCHESTER, NEW YORK, ASSIGNOR TO GLEASON WORKS, OE

vention is illustrated, in a preferred 'embodiment, in Figs. 1, 2 and This gear isprof vided With longitudinally curved teeth 10 which are preferably otistraight profile and V 1 which are of rack sectionandconstantpitch, as shown particularly in Fig. 3, along the straight line G Which is offset from ,the axis 11 ot the gear. The teeth ot' the gearare ot 7 tore ofconstantlvchanging radius. WVhil'e Figs. 7 and 8 are a, diagrammatic plan vieW' and side .e-l vation respectively illustrating the method of cutting, according to this in venti on, the gear or larger nlemher or a pair which may mesh sele otivelvivith a'xvorm or with a mating pinion produced wit li an ad ditional generating roll;

- this gear can be produced by the use ot vari oustool 1neans,it has been discovered that" it can be out most advantageously with a ta-, pered hob suchas illustrated diagrammath cally at 13 and that it can be finished bythe hob Without resort to the usual generating roll. This gear, as above stated, can be meshed with either a taper Worm corresponding to the hobyor with a mating generated a pinion. Thervvorm may be producedginany suitable manner. The-mating pinion may also be produced in any suitable process but preferably is manufactured by rotating a hob representing the hasi gear in continuous engagement ivith the pinion-blank while imparting a relative rolling motion between. i

said hob and blank in the manner of agear 'meshing with its mating gear. One or both members of a pair of gears constructed QC".

cording to this invention may, therefore, be produced 1n a hobbmg operatlon wlth a consequentdecrease in cost and with increased speed of productlon. The production ot one member of a pairof gears having-align]arly disposed axes in a hobbing operation without roll, moreover, permits 01 employingsimplified forms of machinery, eliminating the rolling motion, and further expedites the opera tion andreduces the costs.

.The principles, underlying the present in vention and upon which the structure and arrangement of the mating gears are based, are best explained by a consideration of the theor' of mesh of hyperboloid gears. Figs.- 4 am 5 show apair of such gears in intermeshing relation. The gear 15 rotates upon an axis A, While the gear 16 rotates on an axis A which axes are parallel to the plane otthe paper in Fig. 4, but are offset from one another at a distance E, Fig. i V

LetN represent thenumber of teeth in the I gear and No the number of teeth in the gear 16, so that the tooth ratio is N/No. The.

tooth shapes and characteristics of mesh depend solely upon theabove ratio, but for convenience in the following explanation a velocity analysis will also be made.

If'a point P; Figs. 4 and 5, beassumed to travel in space along any assumed line, while thetWo gears 15 and 16,rotate on their axes, point P-will trace one path on'the gear 15 and another path on the gear 16, which paths join at P. "Such a point P can be a point of mesh or contact between thetwo gears when the tangents to thetwo paths coin- Y cide,tl1at is,.when these paths have a. comvelocity between the two gears is in thedirec: ,tion of the common tangent. The directionv montangent at P, the tooth inclinationlhemg assumed at will, The relative sliding of a tangent tothepaths isidentical with'the direction of the relative velocity and theexistence of a. common tangent at P, therefore. lndlcates relative velocities having the same directions.

Let itbe further assumed that the absolute velocity ofpointP is in a plane parallel toithe axes A and A0. Let'the following 'symbolsrepresent the values indicated:

i p W=the absolute velocity of P in a plane parallel to the axes A'and'Ao. p

a,'a0=the. angles between the'di- ,rection'ofWandtheaxes and A0 respectively. '1 Vs =the relative velocity component of P withrespect a gear 15 in the direction shown in r 3 Vn=the relative velocity compolocity of P with respect to;

a the: gear 16. i r 9., Q the angular velocities of tively. I Z, Z0=the constant vertical dis- 7 .tances ofvthe plane of travel of I from the axes A. and A0', respectively. (Z, do=u1e distances of P from the axes 'A and A0, respectivelv, in llOl'lZOll t-Zdj Pl'O jection, Fig. 4.

for the axes and A01,

above given, the followingresult isjol'ita incd do Z0 cos do? being assumed constant. 'For other points in the same planeyas Figs. and 5,1 the r t' g a 10 S d g I g g points lie in a straight line G passingthrough the pointlO and only points llyingriirsuch straight line arehcapable of: producing rela tive paths with accommon tangent. Hence the line G is the line of actionhetweenthc gears .15 and 16 respectand substituting in this equation the values is always the' same; hence all such With the directions'of rotation of the gears and 15 and 1.6. indicated'in Figs. 4 and 5, the. following values of componentvelocities exist Considering firstthe condition represented The :last equation is'a constanh'jao andla two gears 15 and lG-Vand the two pitclihyperboloidscontact with one another alon tl straight line of. action G and the threads or teeth of correspondingI'gearswill? mesh along nens mo :this line. ,Thewlocation: of thislinezcan-be' :found by letting S repnesentrthe. distance lot the point P from O, whence:

do 8 sin (10 Z0 cos a0 tan I 7 S sin a 1 cos a mltanta o 9Z0 LineG is the generatrix ot-thmpitohsurfaces of the gears 15 and 16, which areahyper an n 21 nti -21 20 where L=the lead.per"toothandI-N0,'.'and N, the number ofteeth-,--and substitutingvin the above equations their equivalentvalues given above" and solving the equations-tor 'Z and Z0, the following equations willrbe obtained thatis, the amount of rofis'et of the :twoaxes is equal to E, which :equals 'Z+ Z0.? The value I of. Eis obtained therefore byudding theflast two eqnations,"whence:

21r sin-a0 sine It is tobe noted-that all of the o-ther t actors I L also is a constant and "consequently the gears 15 and 16 will be ofconstant pitch along the line G1. I

The gear '16 can also 'beconsidered as a hob. This hob will be cit-constant pitchalong the line G and preferably of rack section along this line. It will therefore producea gear haying teeth of constant pitch substantially'of rack-section along the line G when of the last-equation being constants, the lead' it is rotatediniengagement with thegear 7 blank. 'Thehob is formedby longitudinally gashing and relieving a tapered worm to producecutt-ing teeth of rack-section and iconstant pitch in a plane offset fi'om'the: axisofthie' hob, as more fully described hereinafter.

This hob can'-me-sh"in"t-he same waywith fifl 3 SHIEGO 158111-01 different gears 15"so long asftheir' angles'a tan a L N r and toothfinu mbers N ful'fillthe equation a tanao sinvao t glvenfabove tor Z0. The =too thnumber N V v ,,'can be expressed as a function of. a:- as tol'. "The-distance between the a-xes'iA- and A0, lows;

-"21i'ZO "1" '211-Z0 'No R. F[' L tanao L sin aoil a j'llhe gear prod'uced may meshw ith a' worm' correspond ng-in structure mehe hobwhen 7 arranged with its axisofi se-t from the: axis o f The" gear, as.

the wormfby the distance has already been mentioned,- may also form one of a pair of lmrg-itudinally cury ed tooth geais inwhich-the other member wi l l preferably be pr-oducec lin ahobbing operation employing a generating roll and; according to a method novel withthisnnventionin which the hob -and= pinion b'l ank arerolled together in the manner of a gear meshing with'its mating gearQ. The principles upon which 1 the production oi this conjugate bevel pinion is based are illustrated diagrammatically inFigure 6. 'It has been found that-a second fihob 15 can be made to mesh with the'h'ob 16 in the same anotion about the axis of saidgear '15. "The counter hob must of course fulfill =theabov-e equation for N. Itis, therefore, possible W-iththisinvention to produce a pair of bevel larger lmemberioi the pair, without a genergears by 'hobbing one member, preferably the ati-ng rollhjand by cutting the mating gear 7 with a counter hobwhile providing a'relatiye generating "movement between theycounter hob and "the gear blank about the apex of the blank as if the blank were rolling on its inating'gear. v

Themethod of producing abevel pair a ccordingto thls' nvention 1s illustrated dia grammatically 1n F1gures7 to 10 1nolus1ve,;

Figures- Wand 8 illu-stra-ting the manner of producing one member, preterably thelarger IOU member, Without generatingroll and Figures gram- V k 7 ctwith a'bevelgear blank 21, with the axis 22 of the hob offset from the axis 23 ofthe gear blank 9 and 10 showing the manner ot'pr-o-clucing 0 a c n Hga te gear in a generating operation, '1 InFigure 7 ata'per 11013 20 is shown d a "matically, arranged in cutting; conta by the distance E determined as above de r scribed. .For producing the gear, the hob 20' and the blank 21 are rotated about-lthelr re-fi spectlve axes in timed ntermcshing relation to 'efiect a continuouscuttingvand indexing action between hob and blankand simulta- V neously "arelative. -feeding movement. is i-mnoted that themanipulation ot the hob and.

. movement described so that-the blank can be. out without resorting to a generating roll preferably, and this counterhob Wlll bQwPO parted be-tween the hob and bl ank, preferably parallel with the blank axis 23 to obtainthe desired tooth height on the blank, so that in i effect, the hob is sunkeinto the blank. to the full depth of the toothbeing cut. Itis to be blank comprises exclusively the cutting and indexing. rotation and the simple feeding and consequently the gear can be very-rapidly manufactured. In cutting the mating gear 25, a counter hob 26 will be employed,

sitioned relative to the gear blank25 so as to represent the gear'21. Thecounter hob and blank are rotated about their respective axes i 27 and 28 to produce a continuous cutting and a similar Il'lGCllfiI1lSm.. 1 It will thus be seen'that the gear 21 may i be cut in a simple and rapid manner by nere indexing action and simultaneously arelative generating roll is imparted between the counter hob andblank as though aboutthe axis 23. ofthe Inate gear 21. -The generating roll about the axis 23 is added to or subtracted from the indexing rotation oi the lie-b or blank about this same axis. vIna machine for producing the gear25, this would be accorn plished through the use'ot a differential or ly sinking the hob into the blank without a generatingroll, whilethe' mating gear orpin- 7 ion 25 is cut with a similar hob in "a. rapidand practical manner "involving a relative generatingroll for which the mating gear21 is the basis] Asalready of action G abouttheaxis of the gear generates a hyperboloidal surface, This is shown at30, Figure 11, in connection with a hob 13 constructed according to this lnvention and at 32 Figure 2, in connection Withthe gear 14 which may be produced by thehob 13.

g The angle aand theoifset Z are so chosen that the said hyperboloidalsurface approximates either the pitch cone of the gear or the coni-;

' cal surface which lies miclway between the 3 root and face cones of the gear. The profile.

32 of such a-hype-rboloidal surface isshown in Figure 2 as tangent tothe profile 340i? the latter of such conical surfaces. 1 e

y The tapers of hob'and counter hob can be made alike when'theh'ob construction corre- Z0 which reduces, No to the form sponds to the'above equation for the .value of In this case, the formula. torN given above.

reduces to:

- 7 sin ao c'osa In practice, the hob and counter hob ar-e stated, the rotation of the line ows;

being equal to unity,

preferably alike in construction and in fact one andrthe same-hob may be employed as both hob and counterhob. This hob will cut 1 the gear without generatingroll and the mat ing pinion with a, generating roll correspond ing to the rnesh between-gear 'ancbpinion, as already described with reference to Figures 9and-g10. it Theconstruction of the hob is shown in Figures 11 and 12. The hob has generally the form of a taper worm gashed longitudinally produce cutting blades 36' of rack section and constant pitch in a plane 37, Figure 12, offset from the axis A0 of the hoba distance Z0, as heretofore described. The cutting faces 38 of the cutting teeth 36 of the hob. are preferably though not necessarilylocated in said.

plane 37h For producing the hob, the relievingtool 39 is led at a uniforinlead along the line of action and is; preferably. positioned above center corresponding to the desired off se-t of the hob. With! the use of rake flutes or fluted as at 35 andrelieved as shown to 35 such as shown,'in'1proved cuttingjqualities are combined in this type oftapered hob with mathematical correctness The hob can cut gears of various tooth numbers N and taper angles ahaving the relations expressed in the simplifiedequation' for N already given. The taper angle a, not the cone angle, maybe accurately determined by solving for d in the last. equation for Nnbove. The angle a is required for hob set-tings. In cutting the gear,.the hob offset is Z +Z0 which can be obtained from the above" equaltm . tions. The. inclination. of the yhob iaxisis a0 f a). In cutting thepiniom the hob fdistance is Z- Zo and the inclination of the hob axis is a0+ (90 a). A'hob can cut practically all bevel gears corresponding to: bevel pinlons of a given tooth. number irrespective of theircone angles and a wide range of bevel gears can therefore be cut with ,coinparatively few nhobs,

' WVhenthe same hob is used for cutting both members of a pairofbevelgearaas is pref erable, the data for the 1nen be1 *wliicli {is llU produced-without roll canfbe obtained asflfoli whichtoi'mulamay readily I the above equations. i

along ast-raight IineJ fISe't-from the axis .40

of this gear as already described, The teeth f 44 of the pinion 45 are longitudinallycurved i and are conjugatetto'those of the gear; -;The

teeth of the pinion are preferably produced j in'the hobbing'generating process described? wlth reference toF1gures'9 and 10.

In Figure 14, I have shown a pair o ta: pered gears constructed according to this vent-ion and arranged with axes no-nnnt sec-ting and'nomparallel, comprising a taperworm 5.0, and a mating tapered gear 521 such as might be produced by rotating the worm in continuous cut-ting and indexingcngaga ment with the gear, according to the method described with reference to Figures 7 and'S. Each of these gears will be of constant pitch along the straight line G oifset from their re spective 53 and 54. The worm 50 will be of the same construction as-the hob employed to produce the gear Preferably the worm 50'willbe multiple threaded as shown, to ob tain a suitable ratio N/No. The correspond ing hob used to produce the gear 52 will therefore be multiple. threaded also and of same number of threads as the worm. In Figures 7 and 8 and in other figures oi the drawings. the hob axisis shown inclined an angle other than a right angle to'the axis'of the gear blank as this illustrates a general solu tion ot-the problem of correctlyproducing a tapered gear by a bobbing process without roll. In practice;howeveryit is most usuai to mount a pair of tapered gears so that their axes are at rightangles and this mounting I is illustrated in Figure 1a, the axis 53 or the worm being at right angles and offset i'rom the axis 54- of the gear 52. It will be understoodthat in this case the axis of the taper hob used to produce the gear 52, and which corresponds in structure to the worm, will be positioned atright angles to the axis of-the or customary practice in the gear art, and as may be applied to the essential features hereinbefore set forth and-as fall within the scope of the invention or the limits of the appended claims. v 7

Having thus described my invention I claim is:

1. A tapered gear having longitudinally curved teeth and of constant pitch along a straight line offset from its axis.

What

2. A tapered gear having longitudinally curved teeth of straight profile and of racksect-ion along'a straight line offset from its axis.

3. A pair of longitudinally; curved tooth bevel gears, 'one of which is of constant pitch along a. straight line offset from" its axis and the other ofwhich isprovided with teethcon- 1 generated.

4. A'pair of gears provided with longitudir nally curvedteeth and adapted to mesh with. I axes non-inters cting and non-parallel, each pitch-along a straight Y of which is of constant line. offset from ts EtXlS.

5. A pair of tapered gears providedwithfi longitudinally curved teeth and adapted tor mesh with axes non-intersecting and nonparallel said gears. contacting along: a

straight line offset from t-he axes oi both I 6. A pair of tapcred'gears adapted. tomesh 1 with, axes non-intersecting and non-paral lel,=

gears.

one otwh-ich' is providedwitlli longitudinal y curved teeth, said gearwbemg of constantpitch along a straight line. offset from :its

axis. Y

which is a gear such as mightbeprodu ced: by

7. A pair of gearsmeshingwith axes non intersecting and non-parallel,- one-- of1iwlrich is a worm of constantpitch along a straight lineotfset from its axis and: the other of- 1 gate to. those oi the first gear and moldedo said worm when the axis of the worm is angul I larly disposed with reference, to. and offset from theaxis of a gear blank while the two elements are'r tate-d in tlmed relation.

8.'A gear having longitudinally curvedv teeth such as might be produced ina blank 7 by a worm of constant pitch along a straight line offset from its axis when the axis of the worm is angularly disposed with reterenceto and ofilset from the'axis of the blank while the two elements are rotated in timed relation;

loo

9. A tapered gear having longitudinally V curved teeth suchas might be produced in a gear blank by a taper worm of constant pitch along a. straight line'otlset from its axis when the axis or" the worm 1s angularly disposed with reference to and ofiset' from the axis ofthe blank while the two elements are rotated in timed relation.

10. A pair of gears one of which is such as might np o d by a worm hob when the axes of the hob and blank are arranged to be non-intersecting and non-parallel and are maintained in fixed relation while said hob and blank are rotated about their respective axes in timed relation, and the other of which is such as might be produced by a worm hob when the axes of said hob and a gear blank are arranged to be non-intersect ing and. non-parallel and the hob and blank are rotated about their respective axes in timed relation while a relative rolling movement is imparted between hob and blank.

11. A pair of tapered gears one-0t which is such as might beproduced by a tapered hob when the axes of the hoband of a gear blank are arranged to be non-intersecting and non-parallel and'are maintained in fixed rela- 7 tion Whiles'aidhob and blankarerotated about their respectiveaxesin timed relation,

fiand the other of whichis such as might be produced by ataper hob when the axes of saidhob and a gear blank are arranged to be non-intersecting and non-parallel and the it hob and blank are rotated about their respective axes in. timed relation While a relative rolling movement is imparted between the hob and blank in the manner of a gear rollmg on a conical surface. a

12. A pair oft tapered gearsone of which is such as might be produced by a tapered hob of constant pitch When the axes ofthe hob and of a gear blank arh'airainged to be nonintersectlng and non-parallel and are maint ained in fixed relation While said hob and blank are rotated about theirv respective axes in timed relation, and the other of which is suchas might be produced byva taper hob of constant pitch when the axes of said hob and a car blank are arranged to be non-intersectmg and non-parallel and the hob and V blankare rotated about their respective axes in timed relation While a relative rolling movement is imparted between the hob and blank in the manner of a gear rolling 011 a. conical surface.-

13. A pair of tapered gears one of which is such as might be produced by a taper hob, of constant pitch'along a straight line offset from its axis, when the axes of the hob and of a gear blank are arranged to be non-interry in fixed relation While said hob and blank are rotated about theirfrespective axes in timed seating and non parallel and are maintained. 1

relation, and" the other-of which is such as, i

might be produced by a taper hob, of constant pitch along a straight line'otfset from its axis, when the, axes ofsaidhob and. a gear blankare arranged to be non-intersectingl,

and non-parallel and the hob and blank are. A rotatedabout their respective axes in timed a relation While a relative rolling movement is imparted betvveenjthe hob and blank in the manner of a gear rollin on a conical surface.

14. A tapered gearqliaving teeth of cone other: a 1

a i y p 2dr Z I 15. A pairof longitudinally curved tooth bevel gears, one of which has teeth of straight profile and is of rack section along a straight line offset from its axis, and the other'ot ERNEST WILDHABER.

was

00 i which isprovided Withteeth conjugate to i 1 those of the first gear and molded-generated. 

